jdk8-mips64-public/hotspot: comparison src/share/vm/classfile/symbolTable.cpp

--1:000000000000
+:f90c822e73f8
+/*
+* Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*
+*/
+#include "precompiled.hpp"
+#include "classfile/altHashing.hpp"
+#include "classfile/javaClasses.hpp"
+#include "classfile/symbolTable.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "gc_interface/collectedHeap.inline.hpp"
+#include "memory/allocation.inline.hpp"
+#include "memory/filemap.hpp"
+#include "memory/gcLocker.inline.hpp"
+#include "oops/oop.inline.hpp"
+#include "oops/oop.inline2.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "utilities/hashtable.inline.hpp"
+#if INCLUDE_ALL_GCS
+#include "gc_implementation/g1/g1StringDedup.hpp"
+#endif
+PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
+// --------------------------------------------------------------------------
+// the number of buckets a thread claims
+const int ClaimChunkSize = 32;
+SymbolTable* SymbolTable::_the_table = NULL;
+// Static arena for symbols that are not deallocated
+Arena* SymbolTable::_arena = NULL;
+bool SymbolTable::_needs_rehashing = false;
+Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) {
+assert (len <= Symbol::max_length(), "should be checked by caller");
+Symbol* sym;
+if (DumpSharedSpaces) {
+// Allocate all symbols to CLD shared metaspace
+sym = new (len, ClassLoaderData::the_null_class_loader_data(), THREAD) Symbol(name, len, -1);
+} else if (c_heap) {
+// refcount starts as 1
+sym = new (len, THREAD) Symbol(name, len, 1);
+assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
+} else {
+// Allocate to global arena
+sym = new (len, arena(), THREAD) Symbol(name, len, -1);
+}
+return sym;
+}
+void SymbolTable::initialize_symbols(int arena_alloc_size) {
+// Initialize the arena for global symbols, size passed in depends on CDS.
+if (arena_alloc_size == 0) {
+_arena = new (mtSymbol) Arena();
+} else {
+_arena = new (mtSymbol) Arena(arena_alloc_size);
+}
+}
+// Call function for all symbols in the symbol table.
+void SymbolTable::symbols_do(SymbolClosure *cl) {
+const int n = the_table()->table_size();
+for (int i = 0; i < n; i++) {
+for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
+p != NULL;
+p = p->next()) {
+cl->do_symbol(p->literal_addr());
+}
+}
+}
+int SymbolTable::_symbols_removed = 0;
+int SymbolTable::_symbols_counted = 0;
+volatile int SymbolTable::_parallel_claimed_idx = 0;
+void SymbolTable::buckets_unlink(int start_idx, int end_idx, int* processed, int* removed, size_t* memory_total) {
+for (int i = start_idx; i < end_idx; ++i) {
+HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
+HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
+while (entry != NULL) {
+// Shared entries are normally at the end of the bucket and if we run into
+// a shared entry, then there is nothing more to remove. However, if we
+// have rehashed the table, then the shared entries are no longer at the
+// end of the bucket.
+if (entry->is_shared() && !use_alternate_hashcode()) {
+break;
+}
+Symbol* s = entry->literal();
+(*memory_total) += s->size();
+(*processed)++;
+assert(s != NULL, "just checking");
+// If reference count is zero, remove.
+if (s->refcount() == 0) {
+assert(!entry->is_shared(), "shared entries should be kept live");
+delete s;
+(*removed)++;
+*p = entry->next();
+the_table()->free_entry(entry);
+} else {
+p = entry->next_addr();
+}
+// get next entry
+entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
+}
+}
+}
+// Remove unreferenced symbols from the symbol table
+// This is done late during GC.
+void SymbolTable::unlink(int* processed, int* removed) {
+size_t memory_total = 0;
+buckets_unlink(0, the_table()->table_size(), processed, removed, &memory_total);
+_symbols_removed += *removed;
+_symbols_counted += *processed;
+// Exclude printing for normal PrintGCDetails because people parse
+// this output.
+if (PrintGCDetails && Verbose && WizardMode) {
+gclog_or_tty->print(" [Symbols=%d size=" SIZE_FORMAT "K] ", *processed,
+(memory_total*HeapWordSize)/1024);
+}
+}
+void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) {
+const int limit = the_table()->table_size();
+size_t memory_total = 0;
+for (;;) {
+// Grab next set of buckets to scan
+int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
+if (start_idx >= limit) {
+// End of table
+break;
+}
+int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
+buckets_unlink(start_idx, end_idx, processed, removed, &memory_total);
+}
+Atomic::add(*processed, &_symbols_counted);
+Atomic::add(*removed, &_symbols_removed);
+// Exclude printing for normal PrintGCDetails because people parse
+// this output.
+if (PrintGCDetails && Verbose && WizardMode) {
+gclog_or_tty->print(" [Symbols: scanned=%d removed=%d size=" SIZE_FORMAT "K] ", *processed, *removed,
+(memory_total*HeapWordSize)/1024);
+}
+}
+// Create a new table and using alternate hash code, populate the new table
+// with the existing strings.   Set flag to use the alternate hash code afterwards.
+void SymbolTable::rehash_table() {
+assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+// This should never happen with -Xshare:dump but it might in testing mode.
+if (DumpSharedSpaces) return;
+// Create a new symbol table
+SymbolTable* new_table = new SymbolTable();
+the_table()->move_to(new_table);
+// Delete the table and buckets (entries are reused in new table).
+delete _the_table;
+// Don't check if we need rehashing until the table gets unbalanced again.
+// Then rehash with a new global seed.
+_needs_rehashing = false;
+_the_table = new_table;
+}
+// Lookup a symbol in a bucket.
+Symbol* SymbolTable::lookup(int index, const char* name,
+int len, unsigned int hash) {
+int count = 0;
+for (HashtableEntry<Symbol*, mtSymbol>* e = bucket(index); e != NULL; e = e->next()) {
+count++;  // count all entries in this bucket, not just ones with same hash
+if (e->hash() == hash) {
+Symbol* sym = e->literal();
+if (sym->equals(name, len)) {
+// something is referencing this symbol now.
+sym->increment_refcount();
+return sym;
+}
+}
+}
+// If the bucket size is too deep check if this hash code is insufficient.
+if (count >= BasicHashtable<mtSymbol>::rehash_count && !needs_rehashing()) {
+_needs_rehashing = check_rehash_table(count);
+}
+return NULL;
+}
+// Pick hashing algorithm.
+unsigned int SymbolTable::hash_symbol(const char* s, int len) {
+return use_alternate_hashcode() ?
+AltHashing::murmur3_32(seed(), (const jbyte*)s, len) :
+java_lang_String::hash_code(s, len);
+}
+// We take care not to be blocking while holding the
+// SymbolTable_lock. Otherwise, the system might deadlock, since the
+// symboltable is used during compilation (VM_thread) The lock free
+// synchronization is simplified by the fact that we do not delete
+// entries in the symbol table during normal execution (only during
+// safepoints).
+Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
+unsigned int hashValue = hash_symbol(name, len);
+int index = the_table()->hash_to_index(hashValue);
+Symbol* s = the_table()->lookup(index, name, len, hashValue);
+// Found
+if (s != NULL) return s;
+// Grab SymbolTable_lock first.
+MutexLocker ml(SymbolTable_lock, THREAD);
+// Otherwise, add to symbol to table
+return the_table()->basic_add(index, (u1*)name, len, hashValue, true, CHECK_NULL);
+}
+Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
+char* buffer;
+int index, len;
+unsigned int hashValue;
+char* name;
+{
+debug_only(No_Safepoint_Verifier nsv;)
+name = (char*)sym->base() + begin;
+len = end - begin;
+hashValue = hash_symbol(name, len);
+index = the_table()->hash_to_index(hashValue);
+Symbol* s = the_table()->lookup(index, name, len, hashValue);
+// Found
+if (s != NULL) return s;
+}
+// Otherwise, add to symbol to table. Copy to a C string first.
+char stack_buf[128];
+ResourceMark rm(THREAD);
+if (len <= 128) {
+buffer = stack_buf;
+} else {
+buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
+}
+for (int i=0; i<len; i++) {
+buffer[i] = name[i];
+}
+// Make sure there is no safepoint in the code above since name can't move.
+// We can't include the code in No_Safepoint_Verifier because of the
+// ResourceMark.
+// Grab SymbolTable_lock first.
+MutexLocker ml(SymbolTable_lock, THREAD);
+return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, CHECK_NULL);
+}
+Symbol* SymbolTable::lookup_only(const char* name, int len,
+unsigned int& hash) {
+hash = hash_symbol(name, len);
+int index = the_table()->hash_to_index(hash);
+Symbol* s = the_table()->lookup(index, name, len, hash);
+return s;
+}
+// Look up the address of the literal in the SymbolTable for this Symbol*
+// Do not create any new symbols
+// Do not increment the reference count to keep this alive
+Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){
+unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length());
+int index = the_table()->hash_to_index(hash);
+for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(index); e != NULL; e = e->next()) {
+if (e->hash() == hash) {
+Symbol* literal_sym = e->literal();
+if (sym == literal_sym) {
+return e->literal_addr();
+}
+}
+}
+return NULL;
+}
+// Suggestion: Push unicode-based lookup all the way into the hashing
+// and probing logic, so there is no need for convert_to_utf8 until
+// an actual new Symbol* is created.
+Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
+int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
+char stack_buf[128];
+if (utf8_length < (int) sizeof(stack_buf)) {
+char* chars = stack_buf;
+UNICODE::convert_to_utf8(name, utf16_length, chars);
+return lookup(chars, utf8_length, THREAD);
+} else {
+ResourceMark rm(THREAD);
+char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
+UNICODE::convert_to_utf8(name, utf16_length, chars);
+return lookup(chars, utf8_length, THREAD);
+}
+}
+Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
+unsigned int& hash) {
+int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
+char stack_buf[128];
+if (utf8_length < (int) sizeof(stack_buf)) {
+char* chars = stack_buf;
+UNICODE::convert_to_utf8(name, utf16_length, chars);
+return lookup_only(chars, utf8_length, hash);
+} else {
+ResourceMark rm;
+char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
+UNICODE::convert_to_utf8(name, utf16_length, chars);
+return lookup_only(chars, utf8_length, hash);
+}
+}
+void SymbolTable::add(ClassLoaderData* loader_data, constantPoolHandle cp,
+int names_count,
+const char** names, int* lengths, int* cp_indices,
+unsigned int* hashValues, TRAPS) {
+// Grab SymbolTable_lock first.
+MutexLocker ml(SymbolTable_lock, THREAD);
+SymbolTable* table = the_table();
+bool added = table->basic_add(loader_data, cp, names_count, names, lengths,
+cp_indices, hashValues, CHECK);
+if (!added) {
+// do it the hard way
+for (int i=0; i<names_count; i++) {
+int index = table->hash_to_index(hashValues[i]);
+bool c_heap = !loader_data->is_the_null_class_loader_data();
+Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK);
+cp->symbol_at_put(cp_indices[i], sym);
+}
+}
+}
+Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) {
+unsigned int hash;
+Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash);
+if (result != NULL) {
+return result;
+}
+// Grab SymbolTable_lock first.
+MutexLocker ml(SymbolTable_lock, THREAD);
+SymbolTable* table = the_table();
+int index = table->hash_to_index(hash);
+return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD);
+}
+Symbol* SymbolTable::basic_add(int index_arg, u1 *name, int len,
+unsigned int hashValue_arg, bool c_heap, TRAPS) {
+assert(!Universe::heap()->is_in_reserved(name),
+"proposed name of symbol must be stable");
+// Don't allow symbols to be created which cannot fit in a Symbol*.
+if (len > Symbol::max_length()) {
+THROW_MSG_0(vmSymbols::java_lang_InternalError(),
+"name is too long to represent");
+}
+// Cannot hit a safepoint in this function because the "this" pointer can move.
+No_Safepoint_Verifier nsv;
+// Check if the symbol table has been rehashed, if so, need to recalculate
+// the hash value and index.
+unsigned int hashValue;
+int index;
+if (use_alternate_hashcode()) {
+hashValue = hash_symbol((const char*)name, len);
+index = hash_to_index(hashValue);
+} else {
+hashValue = hashValue_arg;
+index = index_arg;
+}
+// Since look-up was done lock-free, we need to check if another
+// thread beat us in the race to insert the symbol.
+Symbol* test = lookup(index, (char*)name, len, hashValue);
+if (test != NULL) {
+// A race occurred and another thread introduced the symbol.
+assert(test->refcount() != 0, "lookup should have incremented the count");
+return test;
+}
+// Create a new symbol.
+Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL);
+assert(sym->equals((char*)name, len), "symbol must be properly initialized");
+HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
+add_entry(index, entry);
+return sym;
+}
+// This version of basic_add adds symbols in batch from the constant pool
+// parsing.
+bool SymbolTable::basic_add(ClassLoaderData* loader_data, constantPoolHandle cp,
+int names_count,
+const char** names, int* lengths,
+int* cp_indices, unsigned int* hashValues,
+TRAPS) {
+// Check symbol names are not too long.  If any are too long, don't add any.
+for (int i = 0; i< names_count; i++) {
+if (lengths[i] > Symbol::max_length()) {
+THROW_MSG_0(vmSymbols::java_lang_InternalError(),
+"name is too long to represent");
+}
+}
+// Cannot hit a safepoint in this function because the "this" pointer can move.
+No_Safepoint_Verifier nsv;
+for (int i=0; i<names_count; i++) {
+// Check if the symbol table has been rehashed, if so, need to recalculate
+// the hash value.
+unsigned int hashValue;
+if (use_alternate_hashcode()) {
+hashValue = hash_symbol(names[i], lengths[i]);
+} else {
+hashValue = hashValues[i];
+}
+// Since look-up was done lock-free, we need to check if another
+// thread beat us in the race to insert the symbol.
+int index = hash_to_index(hashValue);
+Symbol* test = lookup(index, names[i], lengths[i], hashValue);
+if (test != NULL) {
+// A race occurred and another thread introduced the symbol, this one
+// will be dropped and collected. Use test instead.
+cp->symbol_at_put(cp_indices[i], test);
+assert(test->refcount() != 0, "lookup should have incremented the count");
+} else {
+// Create a new symbol.  The null class loader is never unloaded so these
+// are allocated specially in a permanent arena.
+bool c_heap = !loader_data->is_the_null_class_loader_data();
+Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false));
+assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized");  // why wouldn't it be???
+HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
+add_entry(index, entry);
+cp->symbol_at_put(cp_indices[i], sym);
+}
+}
+return true;
+}
+void SymbolTable::verify() {
+for (int i = 0; i < the_table()->table_size(); ++i) {
+HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
+for ( ; p != NULL; p = p->next()) {
+Symbol* s = (Symbol*)(p->literal());
+guarantee(s != NULL, "symbol is NULL");
+unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
+guarantee(p->hash() == h, "broken hash in symbol table entry");
+guarantee(the_table()->hash_to_index(h) == i,
+"wrong index in symbol table");
+}
+}
+}
+void SymbolTable::dump(outputStream* st) {
+the_table()->dump_table(st, "SymbolTable");
+}
+//---------------------------------------------------------------------------
+// Non-product code
+#ifndef PRODUCT
+void SymbolTable::print_histogram() {
+MutexLocker ml(SymbolTable_lock);
+const int results_length = 100;
+int results[results_length];
+int i,j;
+// initialize results to zero
+for (j = 0; j < results_length; j++) {
+results[j] = 0;
+}
+int total = 0;
+int max_symbols = 0;
+int out_of_range = 0;
+int memory_total = 0;
+int count = 0;
+for (i = 0; i < the_table()->table_size(); i++) {
+HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
+for ( ; p != NULL; p = p->next()) {
+memory_total += p->literal()->size();
+count++;
+int counter = p->literal()->utf8_length();
+total += counter;
+if (counter < results_length) {
+results[counter]++;
+} else {
+out_of_range++;
+}
+max_symbols = MAX2(max_symbols, counter);
+}
+}
+tty->print_cr("Symbol Table:");
+tty->print_cr("Total number of symbols  %5d", count);
+tty->print_cr("Total size in memory     %5dK",
+(memory_total*HeapWordSize)/1024);
+tty->print_cr("Total counted            %5d", _symbols_counted);
+tty->print_cr("Total removed            %5d", _symbols_removed);
+if (_symbols_counted > 0) {
+tty->print_cr("Percent removed          %3.2f",
+((float)_symbols_removed/(float)_symbols_counted)* 100);
+}
+tty->print_cr("Reference counts         %5d", Symbol::_total_count);
+tty->print_cr("Symbol arena size        %5d used %5d",
+arena()->size_in_bytes(), arena()->used());
+tty->print_cr("Histogram of symbol length:");
+tty->print_cr("%8s %5d", "Total  ", total);
+tty->print_cr("%8s %5d", "Maximum", max_symbols);
+tty->print_cr("%8s %3.2f", "Average",
+((float) total / (float) the_table()->table_size()));
+tty->print_cr("%s", "Histogram:");
+tty->print_cr(" %s %29s", "Length", "Number chains that length");
+for (i = 0; i < results_length; i++) {
+if (results[i] > 0) {
+tty->print_cr("%6d %10d", i, results[i]);
+}
+}
+if (Verbose) {
+int line_length = 70;
+tty->print_cr("%s %30s", " Length", "Number chains that length");
+for (i = 0; i < results_length; i++) {
+if (results[i] > 0) {
+tty->print("%4d", i);
+for (j = 0; (j < results[i]) && (j < line_length);  j++) {
+tty->print("%1s", "*");
+}
+if (j == line_length) {
+tty->print("%1s", "+");
+}
+tty->cr();
+}
+}
+}
+tty->print_cr(" %s %d: %d\n", "Number chains longer than",
+results_length, out_of_range);
+}
+void SymbolTable::print() {
+for (int i = 0; i < the_table()->table_size(); ++i) {
+HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
+HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
+if (entry != NULL) {
+while (entry != NULL) {
+tty->print(PTR_FORMAT " ", entry->literal());
+entry->literal()->print();
+tty->print(" %d", entry->literal()->refcount());
+p = entry->next_addr();
+entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
+}
+tty->cr();
+}
+}
+}
+#endif // PRODUCT
+// --------------------------------------------------------------------------
+#ifdef ASSERT
+class StableMemoryChecker : public StackObj {
+enum { _bufsize = wordSize*4 };
+address _region;
+jint    _size;
+u1      _save_buf[_bufsize];
+int sample(u1* save_buf) {
+if (_size <= _bufsize) {
+memcpy(save_buf, _region, _size);
+return _size;
+} else {
+// copy head and tail
+memcpy(&save_buf[0],          _region,                      _bufsize/2);
+memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
+return (_bufsize/2)*2;
+}
+}
+public:
+StableMemoryChecker(const void* region, jint size) {
+_region = (address) region;
+_size   = size;
+sample(_save_buf);
+}
+bool verify() {
+u1 check_buf[sizeof(_save_buf)];
+int check_size = sample(check_buf);
+return (0 == memcmp(_save_buf, check_buf, check_size));
+}
+void set_region(const void* region) { _region = (address) region; }
+};
+#endif
+// --------------------------------------------------------------------------
+StringTable* StringTable::_the_table = NULL;
+bool StringTable::_needs_rehashing = false;
+volatile int StringTable::_parallel_claimed_idx = 0;
+// Pick hashing algorithm
+unsigned int StringTable::hash_string(const jchar* s, int len) {
+return use_alternate_hashcode() ? AltHashing::murmur3_32(seed(), s, len) :
+java_lang_String::hash_code(s, len);
+}
+oop StringTable::lookup(int index, jchar* name,
+int len, unsigned int hash) {
+int count = 0;
+for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
+count++;
+if (l->hash() == hash) {
+if (java_lang_String::equals(l->literal(), name, len)) {
+return l->literal();
+}
+}
+}
+// If the bucket size is too deep check if this hash code is insufficient.
+if (count >= BasicHashtable<mtSymbol>::rehash_count && !needs_rehashing()) {
+_needs_rehashing = check_rehash_table(count);
+}
+return NULL;
+}
+oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
+int len, unsigned int hashValue_arg, TRAPS) {
+assert(java_lang_String::equals(string(), name, len),
+"string must be properly initialized");
+// Cannot hit a safepoint in this function because the "this" pointer can move.
+No_Safepoint_Verifier nsv;
+// Check if the symbol table has been rehashed, if so, need to recalculate
+// the hash value and index before second lookup.
+unsigned int hashValue;
+int index;
+if (use_alternate_hashcode()) {
+hashValue = hash_string(name, len);
+index = hash_to_index(hashValue);
+} else {
+hashValue = hashValue_arg;
+index = index_arg;
+}
+// Since look-up was done lock-free, we need to check if another
+// thread beat us in the race to insert the symbol.
+oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int)
+if (test != NULL) {
+// Entry already added
+return test;
+}
+HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
+add_entry(index, entry);
+return string();
+}
+oop StringTable::lookup(Symbol* symbol) {
+ResourceMark rm;
+int length;
+jchar* chars = symbol->as_unicode(length);
+return lookup(chars, length);
+}
+oop StringTable::lookup(jchar* name, int len) {
+unsigned int hash = hash_string(name, len);
+int index = the_table()->hash_to_index(hash);
+return the_table()->lookup(index, name, len, hash);
+}
+oop StringTable::intern(Handle string_or_null, jchar* name,
+int len, TRAPS) {
+unsigned int hashValue = hash_string(name, len);
+int index = the_table()->hash_to_index(hashValue);
+oop found_string = the_table()->lookup(index, name, len, hashValue);
+// Found
+if (found_string != NULL) return found_string;
+debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
+assert(!Universe::heap()->is_in_reserved(name),
+"proposed name of symbol must be stable");
+Handle string;
+// try to reuse the string if possible
+if (!string_or_null.is_null()) {
+string = string_or_null;
+} else {
+string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
+}
+#if INCLUDE_ALL_GCS
+if (G1StringDedup::is_enabled()) {
+// Deduplicate the string before it is interned. Note that we should never
+// deduplicate a string after it has been interned. Doing so will counteract
+// compiler optimizations done on e.g. interned string literals.
+G1StringDedup::deduplicate(string());
+}
+#endif
+// Grab the StringTable_lock before getting the_table() because it could
+// change at safepoint.
+MutexLocker ml(StringTable_lock, THREAD);
+// Otherwise, add to symbol to table
+return the_table()->basic_add(index, string, name, len,
+hashValue, CHECK_NULL);
+}
+oop StringTable::intern(Symbol* symbol, TRAPS) {
+if (symbol == NULL) return NULL;
+ResourceMark rm(THREAD);
+int length;
+jchar* chars = symbol->as_unicode(length);
+Handle string;
+oop result = intern(string, chars, length, CHECK_NULL);
+return result;
+}
+oop StringTable::intern(oop string, TRAPS)
+{
+if (string == NULL) return NULL;
+ResourceMark rm(THREAD);
+int length;
+Handle h_string (THREAD, string);
+jchar* chars = java_lang_String::as_unicode_string(string, length, CHECK_NULL);
+oop result = intern(h_string, chars, length, CHECK_NULL);
+return result;
+}
+oop StringTable::intern(const char* utf8_string, TRAPS) {
+if (utf8_string == NULL) return NULL;
+ResourceMark rm(THREAD);
+int length = UTF8::unicode_length(utf8_string);
+jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
+UTF8::convert_to_unicode(utf8_string, chars, length);
+Handle string;
+oop result = intern(string, chars, length, CHECK_NULL);
+return result;
+}
+void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
+buckets_unlink_or_oops_do(is_alive, f, 0, the_table()->table_size(), processed, removed);
+}
+void StringTable::possibly_parallel_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
+// Readers of the table are unlocked, so we should only be removing
+// entries at a safepoint.
+assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+const int limit = the_table()->table_size();
+for (;;) {
+// Grab next set of buckets to scan
+int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
+if (start_idx >= limit) {
+// End of table
+break;
+}
+int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
+buckets_unlink_or_oops_do(is_alive, f, start_idx, end_idx, processed, removed);
+}
+}
+void StringTable::buckets_oops_do(OopClosure* f, int start_idx, int end_idx) {
+const int limit = the_table()->table_size();
+assert(0 <= start_idx && start_idx <= limit,
+err_msg("start_idx (" INT32_FORMAT ") is out of bounds", start_idx));
+assert(0 <= end_idx && end_idx <= limit,
+err_msg("end_idx (" INT32_FORMAT ") is out of bounds", end_idx));
+assert(start_idx <= end_idx,
+err_msg("Index ordering: start_idx=" INT32_FORMAT", end_idx=" INT32_FORMAT,
+start_idx, end_idx));
+for (int i = start_idx; i < end_idx; i += 1) {
+HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
+while (entry != NULL) {
+assert(!entry->is_shared(), "CDS not used for the StringTable");
+f->do_oop((oop*)entry->literal_addr());
+entry = entry->next();
+}
+}
+}
+void StringTable::buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed) {
+const int limit = the_table()->table_size();
+assert(0 <= start_idx && start_idx <= limit,
+err_msg("start_idx (" INT32_FORMAT ") is out of bounds", start_idx));
+assert(0 <= end_idx && end_idx <= limit,
+err_msg("end_idx (" INT32_FORMAT ") is out of bounds", end_idx));
+assert(start_idx <= end_idx,
+err_msg("Index ordering: start_idx=" INT32_FORMAT", end_idx=" INT32_FORMAT,
+start_idx, end_idx));
+for (int i = start_idx; i < end_idx; ++i) {
+HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i);
+HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
+while (entry != NULL) {
+assert(!entry->is_shared(), "CDS not used for the StringTable");
+if (is_alive->do_object_b(entry->literal())) {
+if (f != NULL) {
+f->do_oop((oop*)entry->literal_addr());
+}
+p = entry->next_addr();
+} else {
+*p = entry->next();
+the_table()->free_entry(entry);
+(*removed)++;
+}
+(*processed)++;
+entry = *p;
+}
+}
+}
+void StringTable::oops_do(OopClosure* f) {
+buckets_oops_do(f, 0, the_table()->table_size());
+}
+void StringTable::possibly_parallel_oops_do(OopClosure* f) {
+const int limit = the_table()->table_size();
+for (;;) {
+// Grab next set of buckets to scan
+int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
+if (start_idx >= limit) {
+// End of table
+break;
+}
+int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
+buckets_oops_do(f, start_idx, end_idx);
+}
+}
+// This verification is part of Universe::verify() and needs to be quick.
+// See StringTable::verify_and_compare() below for exhaustive verification.
+void StringTable::verify() {
+for (int i = 0; i < the_table()->table_size(); ++i) {
+HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
+for ( ; p != NULL; p = p->next()) {
+oop s = p->literal();
+guarantee(s != NULL, "interned string is NULL");
+unsigned int h = java_lang_String::hash_string(s);
+guarantee(p->hash() == h, "broken hash in string table entry");
+guarantee(the_table()->hash_to_index(h) == i,
+"wrong index in string table");
+}
+}
+}
+void StringTable::dump(outputStream* st) {
+the_table()->dump_table(st, "StringTable");
+}
+StringTable::VerifyRetTypes StringTable::compare_entries(
+int bkt1, int e_cnt1,
+HashtableEntry<oop, mtSymbol>* e_ptr1,
+int bkt2, int e_cnt2,
+HashtableEntry<oop, mtSymbol>* e_ptr2) {
+// These entries are sanity checked by verify_and_compare_entries()
+// before this function is called.
+oop str1 = e_ptr1->literal();
+oop str2 = e_ptr2->literal();
+if (str1 == str2) {
+tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
+"in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
+(void *)str1, bkt1, e_cnt1, bkt2, e_cnt2);
+return _verify_fail_continue;
+}
+if (java_lang_String::equals(str1, str2)) {
+tty->print_cr("ERROR: identical String values in entry @ "
+"bucket[%d][%d] and entry @ bucket[%d][%d]",
+bkt1, e_cnt1, bkt2, e_cnt2);
+return _verify_fail_continue;
+}
+return _verify_pass;
+}
+StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
+HashtableEntry<oop, mtSymbol>* e_ptr,
+StringTable::VerifyMesgModes mesg_mode) {
+VerifyRetTypes ret = _verify_pass;  // be optimistic
+oop str = e_ptr->literal();
+if (str == NULL) {
+if (mesg_mode == _verify_with_mesgs) {
+tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
+e_cnt);
+}
+// NULL oop means no more verifications are possible
+return _verify_fail_done;
+}
+if (str->klass() != SystemDictionary::String_klass()) {
+if (mesg_mode == _verify_with_mesgs) {
+tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
+bkt, e_cnt);
+}
+// not a String means no more verifications are possible
+return _verify_fail_done;
+}
+unsigned int h = java_lang_String::hash_string(str);
+if (e_ptr->hash() != h) {
+if (mesg_mode == _verify_with_mesgs) {
+tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
+"bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
+}
+ret = _verify_fail_continue;
+}
+if (the_table()->hash_to_index(h) != bkt) {
+if (mesg_mode == _verify_with_mesgs) {
+tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
+"str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
+the_table()->hash_to_index(h));
+}
+ret = _verify_fail_continue;
+}
+return ret;
+}
+// See StringTable::verify() above for the quick verification that is
+// part of Universe::verify(). This verification is exhaustive and
+// reports on every issue that is found. StringTable::verify() only
+// reports on the first issue that is found.
+//
+// StringTable::verify_entry() checks:
+// - oop value != NULL (same as verify())
+// - oop value is a String
+// - hash(String) == hash in entry (same as verify())
+// - index for hash == index of entry (same as verify())
+//
+// StringTable::compare_entries() checks:
+// - oops are unique across all entries
+// - String values are unique across all entries
+//
+int StringTable::verify_and_compare_entries() {
+assert(StringTable_lock->is_locked(), "sanity check");
+int  fail_cnt = 0;
+// first, verify all the entries individually:
+for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
+HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
+for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
+VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
+if (ret != _verify_pass) {
+fail_cnt++;
+}
+}
+}
+// Optimization: if the above check did not find any failures, then
+// the comparison loop below does not need to call verify_entry()
+// before calling compare_entries(). If there were failures, then we
+// have to call verify_entry() to see if the entry can be passed to
+// compare_entries() safely. When we call verify_entry() in the loop
+// below, we do so quietly to void duplicate messages and we don't
+// increment fail_cnt because the failures have already been counted.
+bool need_entry_verify = (fail_cnt != 0);
+// second, verify all entries relative to each other:
+for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
+HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
+for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
+if (need_entry_verify) {
+VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
+_verify_quietly);
+if (ret == _verify_fail_done) {
+// cannot use the current entry to compare against other entries
+continue;
+}
+}
+for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
+HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
+int e_cnt2;
+for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
+if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
+// skip the entries up to and including the one that
+// we're comparing against
+continue;
+}
+if (need_entry_verify) {
+VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
+_verify_quietly);
+if (ret == _verify_fail_done) {
+// cannot compare against this entry
+continue;
+}
+}
+// compare two entries, report and count any failures:
+if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
+!= _verify_pass) {
+fail_cnt++;
+}
+}
+}
+}
+}
+return fail_cnt;
+}
+// Create a new table and using alternate hash code, populate the new table
+// with the existing strings.   Set flag to use the alternate hash code afterwards.
+void StringTable::rehash_table() {
+assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+// This should never happen with -Xshare:dump but it might in testing mode.
+if (DumpSharedSpaces) return;
+StringTable* new_table = new StringTable();
+// Rehash the table
+the_table()->move_to(new_table);
+// Delete the table and buckets (entries are reused in new table).
+delete _the_table;
+// Don't check if we need rehashing until the table gets unbalanced again.
+// Then rehash with a new global seed.
+_needs_rehashing = false;
+_the_table = new_table;
+}

Mercurial > jdk8-mips64-public > hotspot / file comparison

comparison: src/share/vm/classfile/symbolTable.cpp

src/share/vm/classfile/symbolTable.cpp